What is the derivative of f(t) = (-1/(t+1) , e^(2t-1) ) f(t)=(1t+1,e2t1)?

2 Answers
May 7, 2017

(dy)/(dx)=(t+1)^2e^(2t-1)dydx=(t+1)2e2t1

Explanation:

This is a parametric form of equation i.e. f(t)=(x(t),y(t))f(t)=(x(t),y(t))

In such a case (dy)/(dx)=((dy)/(dt))/((dx)/(dt))dydx=dydtdxdt

Here x(t)=-1/(t+1)x(t)=1t+1 and (dx)/(dt)=-(-1)/(t+1)^2=1/(t+1)^2dxdt=1(t+1)2=1(t+1)2

and y(t)=e^(2t-1)y(t)=e2t1 and (dy)/(dt)=2e^(2t-1)dydt=2e2t1

Hence (dy)/(dx)=(2e^(2t-1))/(1/(t+1)^2)=(t+1)^2e^(2t-1)dydx=2e2t11(t+1)2=(t+1)2e2t1

May 7, 2017

For a parametric function f(t)=(x(t),y(t))f(t)=(x(t),y(t)), the function's derivative is just given by the xx and yy components' derivatives: f'(t)=(x'(t),y'(t)).

So:

f(t)=(-(t+1)^-1,e^(2t-1))

f'(t)=(-(-(t+1)^-2),2e^(2t-1))

f'(t)=(1/(t+1)^2,2e^(2t-1))